Phase locked loops are used in many video systems, such, for example, as in present day VCRs where they are used for the generation of FM luminance signals. When the carrier frequency oscillator is part of a phase locked loop, unless the modulating signal is symmetrical, such as a sine wave, the frequencies of the upper and lower sidebands will deviate from the carrier frequency by different amounts. This results from the fact that the average DC level of the modulating signal causes a shift in the carrier frequency toward one or the other of the side bands whereby the frequency of the sync pulses relative to the carrier frequency deviates from the standard frequency required for proper operation of an associated video system.